> On 23 Feb 2026, at 10:41, Laurenz Albe <[email protected]> wrote: > > On Mon, 2026-02-23 at 10:37 +0100, Attila Soki wrote: >> When upgrading from PostgreSQL 14.4, I noticed that one of my somewhat >> complex >> analytical queries sometimes gets an inefficient plan under PostgreSQL 16, >> 17, and 18. >> Under 14.4, the query runs with a stable plan and completes in 19 to 22 >> seconds. >> In newer versions, the plan seems to be unstable, sometimes the query >> completes >> in 17 to 20 seconds, sometimes it runs for 5 to 18 minutes with the >> inefficient plan. >> This also happens even if the data is not significantly changed. > > This is very likely owing to a bad estimate. > > Could you turn on "track_io_timing" and send us the EXPLAIN (ANALYZE, > BUFFERS) output > for both the good and the bad plan?
Hi Laurenz, Thank you for your reply. Here are the two explains. In order to be able to publish the plans here, I have obfuscated the table and field names, but this is reversible, so I can provide more info if needed. plan-ok: https://explain.depesz.com/s/hQvM plan-wrong: https://explain.depesz.com/s/uLvl Best regards, Attila
